t, x0, y0, x1, y1 = list(map(int, input().split()))
def f(x0, y0, x1, y1):
    return abs(x0-x1) + abs(y0-y1)
l = 0
r = t
while r - l > 1:
    m = (l + r) >> 1
    print("?", m)
    x, y = list(map(int, input().split()))
    a = f(x0, y0, x, y)
    b = f(x1, y1, x, y)
    if a <= b:
        l = m
    else:
        r = m
print("!", l)